Intensity Lab
MMI Scale › Level IX
IX

Violent

Violent shaking · Heavy damage potential

PGA
65 – 124 %g
PGV
116 – 219 cm/s
I II III IV V VI VII VIII IX X

General panic. Well-designed structures thrown out of plumb; great damage in substantial buildings with partial collapse. Buildings shifted off foundations.

Effects

People & Response

  • General panic; widespread fear
  • Difficult or impossible to stand outdoors

Objects & Furnishings

  • Water reservoirs seriously damaged
  • Underground pipes broken

Structures & Environment

  • Well-designed frame structures thrown out of plumb
  • Buildings shifted off foundations; walls collapse
  • Ground cracked conspicuously
  • Considerable damage even in specially designed structures
Typical PGA (ShakeMap) 65 – 124 %g
Typical PGV (ShakeMap) 116 – 219 cm/s
PGA/PGV ranges are approximate; values overlap between adjacent levels. See Instrumental Intensity for details.

Video Example

MMI IX shaking example video thumbnail
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Descriptions are verbatim from the USGS MMI Scale, based on Wood & Neumann (1931) and Richter (1958). Source: USGS Modified Mercalli Intensity Scale .

Instrumental intensity values and PGA/PGV ranges from USGS ShakeMap V4 Technical Documentation (Worden et al.). Intensity Lab reports MMI derived via the Worden et al. (2012) GMICE, interpolated from USGS ShakeMap. PGA/PGV ranges are approximate; actual values overlap between adjacent levels.